WO2008125898A1

WO2008125898A1 - Cap feeding unit having shifted starwheels

Info

Publication number: WO2008125898A1
Application number: PCT/IB2007/002104
Authority: WO
Inventors: Mauro Lenzi
Original assignee: Sidel Participations
Priority date: 2007-04-11
Filing date: 2007-04-11
Publication date: 2008-10-23
Also published as: EP2134635B1; ATE499316T1; ES2364656T3; EP2134635A1; DE602007012772D1; CN101678965B; CN101678965A; MX2009010832A; JP2010523423A

Abstract

A cap feeding unit (1 ) comprising : a first cap feeding line (3) receiving a first row of caps (2), at least one second cap feeding line (4) receiving a second row of caps (2), said first and second cap feeding lines (3, 4) merging into one single cap feeding line (10) at a junction area (9), a rotary drive unit (11 ) positioned in the vicinity of the junction area (9) and including: a first starwheel (13) comprising a plurality of radial arms (15) engaging the first row of caps (2), at least one second starwheel (14) comprising a plurality of radial arms (16) engaging the second row of caps (2) and positioned with an angular shift with respect of the first starwheel (13).

Description

Cap feeding unit having shifted starwheels

FIELD OF THE INVENTION

The invention relates to the container industry, and more specifically to the capping of containers.

Once filled, containers are immediately capped, at a capping unit, with caps supplied by a cap feeding unit at a feeding rate equal to the capping rate (i.e. to the filling rate). Nowadays such a rate can reach up to several tens of thousands units per hour. Therefore, it is critical that the cap feeding unit work with maximum speed and minimum stops.

BACKGROUND OF THE INVENTION

In an ordinary cap feeding unit, caps are supplied from a hopper into a cap feeding line where a single row of caps is moved by gravity towards the capping unit. One drawback of such a technique is that, given the speed of the caps, which is very high, there is a risk of cap jamming along the feeding line. Some manufacturers resolved this problem by providing poka-yoke solutions, see e.g. European patent EP 0 782 888 (Lenzi). However, such a solution increases complexity of cap handling, since ejected caps must be collected and fed back to the hopper.

It is known to multiply the feeding lines in order to decrease the speed of the caps in each line and therefore decrease the risk of cap jamming. However, complexity of such a solution resides in the merging of the cap feeding lines. Japanese patent application JP 2005247444 (Mitsubishi) provides an air-based solution wherein, at a junction area of two cap feeding lines, compressed air is pulsed to the caps to move them towards a single receiving line. However, in such a solution, the risk remains that in the junction area the caps collide and therefore block each other, thereby resulting in cap-jamming. It must be noted that, in addition to the necessity of stopping the machine and detangle the caps, cap collision often leads to bad surface condition on the caps. SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a cap feeding unit allowing increased feeding rates. It is another object of the invention to provide a cap feeding unit with enhanced reliability.

The proposed cap feeding unit comprises: a first cap feeding line receiving a first row of caps, at least one second cap feeding line receiving a second row of caps, said first and second cap feeding lines merging into one single cap feeding line at a junction area, a rotary drive unit positioned in the vicinity of the junction area and including: a first starwheel comprising a plurality of radial arms engaging the first row of caps, and at least one second starwheel comprising a plurality of radial arms engaging the second row of caps and positioned with an angular shift with respect of the first starwheel.

The above and other objects and advantages of the invention will become apparent from the detailed description of preferred embodiments, considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.1 is a partly cut front elevation view of a cap feeding unit according to the invention.

FIG.2 is a side elevation view of a cap feeding unit according to the invention.

FIG.3 is an enlarged cut view showing a rotary drive unit of a cap feeding unit according to the invention.

FIG.4A-4E are schematic elevation views illustrating movement of a cap feeding unit according to the invention. DESCRIPTION OF PREFERRED EMBODIMENTS

Turning to FIG.1 , there is shown a cap feeding unit 1 as part of a container handling machine in which molded containers are rinsed, filled and then capped. Caps 2 are put in bulk in at least one hopper (not shown), for example of the rotating/vibrating plate type, standing on top of a machine frame.

Caps 2 are fed from the hoppers into at least two cap feeding lines, e.g. one first cap feeding line 3 receiving a first row 5 of caps 2, and at least one second cap feeding line 4 receiving a second row 6 of caps 2.

All caps 2 of a same row have their concavity oriented in the same way, preferably upwardly with respect of the machine frame.

The cap feeding lines 3, 4 may be connected to a common hopper, or to different hoppers. The cap feeding lines 3, 4 are preferably formed of stainless steel wire guides.

The cap feeding lines 3, 4 have a horizontal portion which, depending upon the machine speed rate and/or capacity, may run all or partly along the machine frame, either longitudinally or transversely. In the vicinity of a machine frame edge, cap feeding lines 3, 4 each have a bend and, downstream the bend, a vertical portion 7, 8 wherein the concavity of the caps 2 is oriented outwardly with respect of the machine frame.

As depicted on FIG.1 , the vertical portions 7, 8 of the feeding lines 3, 4 run parallel to each other before they merge at a Y-shaped junction area 9 into one single cap feeding line 10, in which caps 2 coming alternately from the first and second feeding lines 3, 4 are fed to a capping unit (not shown), where caps 2 are put on the mouths of the containers and screwed thereto. On FIG.1 , movement of the caps 2 is indicated by arrows M. As caps 2 are moved by gravity in the vertical portions 7, 8 of the feeding lines 3, 4, so that the caps 2 are in permanent contact with each other, the linear pitch P between two adjacent caps 2, i.e. the distance between their central axis along the row 5, 6, is equal to their external diameter.

Cap feeding unit 1 further comprises a rotary drive unit 11 positioned in the vicinity of the junction area 9. More precisely, rotary drive unit 11 is positioned immediately upstream the junction area 9, at the end of the vertical parallel portions 7, 8 of the feeding lines 3, 4.

Rotary drive unit 11 is provided with a bracket 12 fastened to the cap feeding lines 3, 4 and comprises a pair of star wheels 13, 14 which are pivotally mounted on the bracket 12 so as to rotate around a horizontal axis A perpendicular to the moving direction M of the caps 2. More precisely, the rotary drive unit 11 comprises: a first star wheel 13 comprising a plurality of paddle-shaped radial arms 15 engaging the concave portion of the caps 2 of the first row

5, at least one second star wheel 14 comprising a plurality of paddle- shaped radial arms 16 engaging the concave portion of the caps 2 of the second row 6. Each star wheel 13, 14 extends and rotates in a symmetry plane P1 ,

P2 of the corresponding row 5, 6 of caps 2. Both star wheels 13, 14 are fixed to a common hub 17, fixed in turn to a driven rotary shaft 18, so the star wheels 13, 14 rotate simultaneously at the same speed.

In each star wheel 13, 14, the curvilinear distance - i.e. the distance measured along the periphery of the star wheel 13, 14 - between radial ends of two adjacent arms 15, 16 is substantially equal to the linear pitch P of the corresponding row 5, 6 of caps 2, so that the star wheel 13, 14 and the corresponding row 5, 6 of caps 2 mesh as a rack-and-pinion gear. The number of arms 15, 16 and the angular pitch of each star wheel

13, 14 depends upon the diameter of the wheel 13, 14. In the depicted example, each star wheel 13, 14 has eight arms 15, 16 (i.e. the angular pitch is 45°) and has a diameter which is substantially equal to 3 P.

As depicted on FIG.2, the second star wheel 14 is positioned with an angular shift with respect of the first star wheel 13, equal to half the angular pitch between the arms 15, 16 (22,5° in the depicted example), whereby the second row 6 of caps 2 is vertically shifted of half the linear pitch P with respect of the first row 5, and the caps 2 of the first row 5 and second row 6 are alternately chucked, across the Y-shaped junction area 9, to the single downstream feeding line 10.

Accordingly, the flow of caps 2 fed from the first and second rows 5, 6 to the single cap feeding line 10 is precisely controlled, and the risk of cap jamming in the Y section 9 is considerably minimized. The rotary speed of the star wheels 13, 14 is set to such a value that the linear speed of the radial ends of the arms 15, 16 is substantially equal to the linear speed of the caps 2 as if they were freely falling along the vertical portions 7, 8 of the feeding lines 3, 4, so that the caps 2 are not slew down due to the presence of the star wheels 13, 14. As depicted on FIG.1 , the cap feeding unit 1 is provided with at least a pair of air nozzles 19, 20 which are directed both toward the concave portion of the caps 2 and downward, immediately downstream the star wheels 13, 14, in order to accelerate the caps 2 in the junction area 9.

As depicted on FIG.3, the rotary drive unit 1 further comprises a motor 21 , a driving shaft 22 coupled to the motor 21 , and a clutch 23 which couples the driving shaft 22 to the driven shaft 18.

The clutch 23, of the magnetic type, comprises a first clutch disc 24 fixed to the driving shaft 22 and including a first annular set 25 of permanent magnets, and a second clutch disc 26 fixed to the driven shaft 18 and including a second annular set 27 of permanent magnets facing the first annular set 25 of permanent magnets.

Accordingly, the driven shaft 18 is pivotally coupled to the driving shaft 22, so that the motor 21 rotates the driven shaft 18 - and therefore the star wheels 13, 14 - at a predetermined angular speed, as long as no resistant torque applies to at least one star wheel 13, 14 or, in case such a resistant torque applies, until this resistant torque is lower than a maximum clutch coupling torque.

No resistant torque applies to the star wheels 13, 14 as long as the rows 5, 6 of caps 2 and the star wheels 13, 14 correctly mesh (FIG.4A), i.e. as long as there is no interruption in the flow of caps 2.

However, such an interruption may occur (FIG.4B). One arm 15 may then hit the edge of a cap 2 of the next coming row, as depicted on FIG.4C. In such a situation, the corresponding star wheel 13 is blocked in rotation as the resistant torque exerted by the cap 2 is greater than the maximum clutch coupling torque. The driven shaft 18 is then uncoupled from the driving shaft 22 and, in reaction to the hit, the star wheel 13 is shifted back over a small angle (FIG.4D), thereby allowing the cap 2 to move forward. After a fraction of a second, the driven shaft 18 is coupled back to the driving shaft 22, and the star wheel 13 can engage the corresponding row 5 of caps 2 again (FIG.4E).

In a preferred embodiment, the rotary drive unit 1 is provided with means for setting the maximum clutch coupling torque by setting the distance between the annular sets 25, 27 of magnets. In the depicted example (FIG.3), these setting means are means for moving the second clutch disc 26 along the rotary axis A of the driven shaft 18.

More precisely, the second clutch disc 26 is screwed onto a threaded end portion 28 of the driven shaft 18, which is provided with an elongated hole 29. A coupling pin 30 is inserted through both the second clutch disc 26 and the elongated hole 29 in the driven shaft 18, thereby preventing any rotation therebetween. Setting the position of the second clutch disc 29 along the driven shaft 18 is achieved by removing the coupling pin 30, screwing - or unscrewing - the clutch disc 26 and, once reached the desired position, putting the coupling pin 30 back in position.

Claims

1. A cap feeding unit (1 ) comprising: a first cap feeding line (3) receiving a first row of caps (2), - at least one second cap feeding line (4) receiving a second row of caps (2), said first and second cap feeding lines (3, 4) merging into one single cap feeding line (10) at a junction area (9), said cap feeding unit (1) being characterized in that it further comprises a rotary drive unit (11) positioned in the vicinity of the junction area (9) and including: a first starwheel (13) comprising a plurality of radial arms (15) engaging the first row of caps (2), at least one second starwheel (14) comprising a plurality of radial arms (16) engaging the second row of caps (2) and positioned with an angular shift with respect of the first starwheel (13).

2. A cap feeding unit (1) according to claim 1 , wherein the angular shift is equal to half the angular pitch between the arms (15, 16).

3. A cap feeding unit (1) according to claim 1 or 2, wherein the distance between radial ends of two adjacent arms (15, 16) is substantially equal to the linear pitch of the rows (5, 6) of caps.

4. A cap feeding unit (1) according to any of claims 1 -3, wherein the rotary drive unit (11 ) comprises a driven rotary shaft (18) on which the starwheels (13, 14) are mounted.

5. A cap feeding unit (1 ) according to claim 4, wherein the rotary drive unit (11 ) comprises: a motor (21 ), a driving shaft (22) coupled to the motor (21 ), a clutch (23) which couples the driving shaft (22) to the driven shaft (18).

6. A cap feeding unit (1) according to claim 5, wherein said clutch (23) comprises: a first clutch disc (24) fixed to the driving shaft (22), said first clutch disc (24) including a first annular set (25) of permanent magnets, a second clutch disc (26) fixed to the driven shaft (18), said second clutch disc (26) including a second annular set (27) of permanent magnets facing said first annular set (25) of permanent magnets.

7. A cap feeding unit (1 ) according to claim 6, wherein the rotary drive unit (11) comprises means (28, 29, 30) for moving said second clutch disc (26) along the rotary axis (A) of the driven shaft (18).